Mycoplasma Flashcards
Bacterial Resp Disease II
Mycoplasma structure
obligate extracellular parasites
simple structure (plasma membrane, ribosomes and dsDNA)
plasma membrane has variation in the surface antigen leading to evading the immune response
no cell wall (cannot exist in environment)
Transmission ?
mucosal commensals and aerosol in close quarters
does not survive in the environment unless in a biofilm
Pathogenesis ?
- attaches to host cell
- prevents ciliary clearance
- produce ROS and CARDS toxin, leading to H2O2 production and tissue damage
- triggers the immune system (cytokine and chemokine release)
^ once this has all occurred, the bacteria is free to invade other tissues and create autoimmune reactions
Diagnosis ?
bacteriology (slow growing and difficult)
PCR
IHC
serology (antibody)
Clinical Signs ?
(dependent on system)
pulmonary = dyspnoea, mucus secretion, abnormal posture
arthritis = lameness
otitis = circling, abnormal head position
What are the main lesions we see ?
bronchopneumonia / pleuropneumonia
How does Mycoplasma bovis affect cattle ?
enzootic pneumonia and/or bovine respiratory disease complex
grossly, suppurative bronchopneumonia, bronchiectasis, necrosis and purulent exudate visibly in the bronchi on cut surface
histologically, caseous necrosis, neutrophils, bronchiectasis, cellular debris within the primary bronchi and degeneration. fibrosis in more chronic stages
may see fibrin arthritis and osteomyelitis
How does Mycoplasma mycoides subsp. mycoides affect cattle ?
causes bovine contagious pleuropneumonia (a reportable disease in the UK)
acute disease grossly, pleuropneumonia, hydrothorax and interlobular oedema (“marbled appearance”)
chronic disease grossly, necrotic areas on lungs and fibrosis
histologically, serofibrinous/suppurative exudate, coagulative necrosis and interlobular septa
How does Mycoplasma ovipneumoniae affect sheep ?
similar lesions to M. bovis but in big horned sheep
grossly, suppurative bronchopneumonia and bronchiectasis
histologically, lymphoid hyperplasia, bronchiectasis and bronchial epithelium hyperplasia, fibrosis
May also see arthritis, otitis, endometritis and sinusitis (especially in the horns)
How does Mycoplasma capricolum spp. capripneumoniae affect goats ?
causes contagious caprine pleuropneumonia (a reportable disease in the UK)
grossly, fibrinous pleuropneumonia with a lot of oedema, necrosis and neutrophils. can see polyarthritis if animal is young. bronchiectasis is common.
histologically, fibrinous and suppurative pleuropneumonia and bronchiectasis
may also see corneal oedema (keratitis affecting cornea) as a chronic lesion
How does Mycoplasma agalactiae affect sheep/goats
Septicaemia, before the bacteria localize in the mammary gland, leading to lymphohistiocytic interstitial mastitis and lymphoid follicles with severe fibrosis
may also see keratitis and arthritis
How does Mycoplasma hypopneumoniae affect pigs ?
causes enzootic pneumonia, a chronic but non-fatal disease in young pigs.
grossly, bronchopneumonia, firm/rubbery/pale red to tan lungs, bronchiectasis
histologically, lymphohistiocytic inflammation, lymphoid nodules associated with bronchiectasis
What does Mycoplasma cynos do to dogs ?
causes canine infectious resp disease
grossly, cranioventral lung lobes are grey/purple in colour and consolidated
What is the main thing to know ?
Mycoplasma causes neutrophilic bronchopneumonia with bronchiectasis.
